In order to clarify the changes in the intrusion distance and movement speed of saltwater as the flow velocity and salt concentration change,we carry out a study on the saltwater intrusion characteristics in the riverbed of Qingnian reservoir area,and analyze the influence of river inflow conditions and salinity changes on the saltwater intrusion process.We conduct experimental research by simulating the process of saltwater intrusion along the riverbed in Qingnian reservoir area in a small generalized flume.The results show that under the restriction of upstream flow,the intrusion distance of saltwater remains stable under the action of runoff,and the intrusion process is significantly affected by the tributary diversion.Due to the impact of the upstream flow on saltwater at the branch point,most of the saltwater is dispersed and flows out of the branch point,while a small amount of saltwater remains stable and continues to intrusion along the left bank.As the water depth increases,the sensitivity of the intrusion distance to the concentration change decreases.Under the same water depth condition,the increase in salt concentration will accelerate the intrusion velocity,and the shorter the intrusion time required;under the same concentration condition,the increase in water depth can significantly improve the intrusion velocity of saltwater.